Whether or not I need something is beside the point. The question is 'Do I want it?'
While in the process or setting up my workshop, I read quite a bit about the Cyclonic Dirt Separator - a device that allows the heavier particles of debris, such as wood shavings or sawdust, to settle to the bottom of a container, while the finer particles go into your vacuum's filter.
I had to have one.
But I didn't particularly want to spend a load of money or fabricate individual pieces. So this Instructable was born, using (almost all) store-bought parts.